Sintered alumina bodies are excellent refractories for use as kiln furniture, but suffer from cracking or spalling when subjected to rapid temperature changes. The object of the present invention is to improve the thermal shock resistance of sintered alumina bodies by incorporation of coarse grained silicon carbide in the bodies.
Prior patents have suggested the incorporation of silicon carbide in alumina bodies. U.S. Pat. No. 2,770,552 teaches adding 17.5 to 25% silicon carbide to alumina, and firing shaped bodies formed therefrom at 3,000.degree.F and higher. Such bodies are disclosed as having better high temperature strength and resistance to breakage than silicon carbide or aluminum oxide bodies. Because of the relatively coarse alumina employed a relatively high firing temperature is required by Pieper to achieve acceptable strength in the body. Such firing converts part of the silicon carbide to silica which in turn reacts with some of the alumina to form mullite, tending to cement the body together. Another patent, to Davies et al, 3,230,100 teaches the use of from 50 to 70% of silicon carbide in an alumina-silica system.